Background...

In the Spring of 2018, due to my increasing interest in modeling early Illinois Traction System, I developed a 3D print of a GB hopper gondola for the ITS based off a Pennsylvania Railroad plan as documented on MRH here.  That model is for sale on my Shapeways website.  A gentleman by the name of Robert McGlone purchased one of those models and detailed his construction of it on the early rail groups at groups.io, the yahoo groups replacement ( #45931 for anyone looking for it).  Below is his finished model of the GB gondola hopper that he made for the Central Railroad of New Jersey. 

As a result of his documented build, I was able to sell several of these GB hoppers through Shapeways.  Wanting some more practice and seeing an opportunity there, I communicated my appreciation to Robert for his efforts.  This then led to him asking if would be interested in designing a model of the HKa hopper for the P&R as seen in the first post above. 

More info...

Some history on these cars: the P&R was looking for a new design hopper bottom gondola to replace their 1889 design HPa twin hopper bottomed gondola car. They settled on a wider and shorter car that used the new style King Patent hopper doors. Apparently, at this time, it was considered more advantageous to have a gondola with a mostly flat floor than a true self-clearing hopper/gondola car. A car like this could be used for other gondola loads [scrap, pipe, timbers, rail, ties] when not hauling coal. Roughly 10000 of these cars were acquired from 1895 to about 1902. All of them were equipped with pressed steel bolsters, Fox Trucks, air brakes and knuckle couplers. While they looked like this model as originally built, over time it's likely that all were changed to a single brake wheel moved over to the new standard left-hand end of the car.  Some of these cars stayed in service to the late 1920's. The lettering style was also changed over the years to add 'THE READING' logo to the left car side. This prototype was first made available as an HO model as a flat resin kit by Virginia Foundry back in 2011. One run of around 67 kits was done - and that was it.

Robert sent me his original prototype HO scale model of the P&R HKa hopper as he and a friend were the ones that were behind Virginia Foundry.  Their interest lies in the early turn of the century cars and before.  Using his original model along with plans that he sent me, I recreated the model using SketchUP, a free 3D modeling program.  The model I created looked like the one below.  The 3D version an upgrade over the previous Virginia Foundry resin kit. Three noticeable improvements are the prototypical tapered side stakes, the pressed steel corner brackets, and the one piece body. The one-piece body is a huge time saver, with queen posts and hopper latching mechanism already completed, such that the customer only needs to install trucks, couplers, truss rods, and the Tichy brake system.

I have about 20 progress shots of the model as I was "building" it in Sketchup.  If you want to see them or the steps I went through to create this, let me know and I will add a post about it.  

The 3D print

Robert ordered the first print from Shapeways.  This is what it looks like. 

You can see the material is rather translucent.  It needs to be cleaned thoroughly to remove the supporting wax layers.  At this point, one can see why the 3D print is by far easier than a resin kit would be.  At this point, its add some brake details and grab irons, trucks and couplers, and paint and decals (decals are available for this model).  I did have a few minor issues that I will discuss in a later post along with how I corrected those issues. 

The finished model...

This is what the finished model looks like. Below shows the finished brake system and piping. 

Below shows the ratchet side of the car without decals. 

Decaling in process. 

The finished car. 

What's the time frame for those of you still reading along?  It took me about a week to make the 3D drawing in Sketchup.  It was nice to have an actual model in hand instead of just working off drawings.  It took about a week for the model to be printed and shipped.  Then Robert added the details, painted, and decaled in about a week.  

It is still surreal to me that this process actually works to produce a model.  I've enjoyed making new friends through this hobby and meeting new people with similar interests.  Robert says he has some more models he'd like for me to work on so we will see what happens.  

Interesting...

Yes, could you provide the steps/views during the SketchUp CAD work?   I have a huge impediment thinking of going from step 1 to step 99(so to speak).   Seeing how someone else breaks down a project like this would be most helpful.

thanks in advance.

mistakes...

Hey, mistakes happen.  In the original print, I didn't do a good enough job of deleting interior lines.  To get these things to print well, the inside needs to be as "open" as possible with no interior walls blocking of parts of the inside.  When I copied and pasted something, it looked "right" on the SketchUp model but didn't get translated to Shapeways correctly.  That resulted in three of the Queen posts "falling off" during the initial washing.  The one that I drew first and didn't copy turned out fine.  In the Shapeways renderings below, you can see that above three of the queen posts, part of the sill beam is missing.  I didn't catch this in my initial scan.  It printed this way but when cleaned, the parts separated too easily as there was minimal plastic holding it together.  

This shows the corrected renderings after I fixed them. 

Have you tried printing it as separate parts

to eliminate the carved from one block look of typical 3 D printed models? Perhaps even leave out the sides and other wooden parts and let the modeler add them from strip material.....DaveB

Nice!

Truly amazing!

Replies...

@ DaveB - leaving out the wood parts... I had never thought of that.  Would be pretty simple to add strip wood back into place.  My only concern would be if the stakes would be too fragile to be by themselves.  Some thin parts I've done have warped as well....

@ Bud - Thanks!

Possibly silly question

I don't think I've seen it expanded in the blog - what does P&R stand for?

Philadelphia & Reading

Which for a brief moment in time was the largest railroad in the US and the largest (in value) corporation in the US.  It became the Reading Company and ultimately part of Conrail.

Reply to Jeff

Sorry... P&R refers to the Philadelphia and Reading Railroad. 

Project Cost

Truly amazing work - I'm impressed.

What did the cost of model, all in, wind up being.  I know the effort to create the 3D model would have been extensive but I'm more interested in the production costs.

Cheers

Kim

Reply to kaz...

Hey... fair enough question.  The baseline price set by Shapeways is $44.45.  I have it marked up to $49,95 for a $5.50 profit.  Seemed fair to me and I wanted to keep the price under $50 to help it seem more palatable.   Again, the great advantage is by far the ease of assembly by adding a few details resulting in a truly unique car.  Does that answer your question? For those interested, it is located here. 

Reply to Loren...

Hey Loren...

This is my thought process.  I guess there is more than one way to skin a cat, this is how I skinned this gondola...

I started with the floor.  As I hadn't done full hopper underbody detail, I didn't want the sides of the gondola interfering with cutting and pasting so I went that route.  

Then I set about to work on the hoppers themselves by first making the basic shape and then adding the details of the doors, etc. 

Then the bolsters

more progress

Then I added the hopper door details...

In the above photo, you can see where I've added lines in the floor to eventually make the groves between the boards to simulate actual boards.  Then I added the side boards and the end braces.  I am really pleased with how the corner braces turned out.  I had to scale up the model so the circles would work and then scale it back down. 

Final steps...

Then I worked on the stake pockets and posts. 

Then added the end brake platforms along with NBW on the ends. 

Resulting in the finished model...

I did add interior boards but I don't have a picture of that. 

...

…Not even close...at least, it's not near as exertive as scratch building the model from styrene.

Production costs with Shapeways are high and slated to go *higher.*

My production process is looking towards actually adding a printer to my workspace.  The Anycubic is catching my eye - and with Shapeways burning my pocket from the wrong direction, I'm queuing it up for my next big jump...

Thanks for the drawing process

I just have trouble forcing myself to learn and just try.....of course that goes beyond 3D drawing.   Trying to get some other projects done, but one of the first things after that is to finish my 3D printer build to do some car sides and details that don't have to be super fine or super high quality finish.

One thing I've heard that can help mass produce cars is to 3D print a master and use that to cast resin multiples.   Frank Hodina from Resin Car Works suggested that you only need to worry about one or two good 3D prints, then find someone who does resin casting and just have them do it that way.   It still is more expensive than plastic kits, but if you just have them do the basic body, and you do all the sourcing of trucks/couplers/grab irons etc, it is still cheaper than an ExactRail/Tangent level car.   Of course, depends on how many of a car you need.   I need around 100 IC Centralia built 83 ton three bay offset side hoppers.   Even a one piece body x 100 is a lot of time and money investment.

Hoppers

With that many cars, resin casting is the way to go.  I was visiting with a friend of mine who does 3D printing and the biggest barrier to 3D printing is time.  He has some kits that take 2 or 3 days of printing to get one kit (why he has 5 printers going almost 24x7.)  For a HO triple hopper, and one printer, it could take as long as a year, printing non-stop to make all the parts for 100 cars.

The big cost with resin casting is the RTV molds and designing the master/mold is critical.  Big undercuts are killers.  You will probably get 25-40 pulls out of a mold before it wears out (cracks/tears), for 100 cars you will need 3-4 sets of molds.  Resin casting is also not speedy either, the mold has to be prepped, the resin mixed, the resin poured, the casting cures, the casting is removed.  Rinse, repeat.  You can get 2 maybe 3 castings an hour.

With hopper cars there are issues with the ends and the frame that don't cast well, so a one piece casting would be very difficult.  It would probably have to be a 5 or 6 piece car (2 sides, 2 ends, slope sheets/hoppers, underframe).  If you wanted the interior of the car sides to be "offset" too, that would require 2 part molds for the sides.  Not being negative, just pointing out some things you will have to design.  If you are making a 3D print master then you will have to design the master as a resin mold master, not necessarily as a "car".

I have no  idea what the car you want looks like, but if there are commercial cars that are close, you might be able to cast/print just the signature parts to modify the commercial kit.

Casting

I got my HKa 3D printed car yesterday.  Mixed impressions.

The design itself is really nice.  It would take a lot of work on my part to get that level of detail.  There is no way I could get the corner braces with that level of detail.  Very happy with that.

The Shapeway's printing is a bit of a disappointment, there were several voids in the floor of the car along the centersill, with holes about 3 scale ft long and 6 scale inches wide.  I normally add weights to the floors of my hoppers (resin or scratchbuilt), so it won't matter really.  More flash than I expected, but that's not a big deal, I get way more flash on a resin kit, just surprised there was any on a 3D printed model.  I don't consider this a design flaw, I bought two of the GD gon printings and they didn't have those flaws in them, it seems to me to be a problem with the production.

In the picture below, between the bolster and the hoppers, you can see the holes on both sides of the center sills, also between the hoppers there are small holes.  Above the big hole is what appears to be a triangular void in the floor, inside the printing.

I was also surprised by the amount of residue on the printing, it was positively sticky and had visible sheen from whatever oil or solvent that is used in the manufacturing process.  It will require a thorough scrubbing to clean up.

Overall I was very happy with the car and the level of detail.  This is not critical of Mr. Forbes, I would be interested in future products of his (this is the third car I've bought from him), but wanted to make sure he was aware of Shapeway's issues and to let other modelers know that there still are some quality control issues with 3D printing.

The Shapeway's printing is a

In my experience, "voids" in the way you describe/picture them are not the fault of the printing process, but originate with faults in the model - usually having to do with otentation of faces (reversed, inside-out. Yes, it makes a difference!)

I've not seen "flash" on a FUD print from Shapeways, either. Again, my first inclination is to look for extra faceson the model, perhaps due to reference points or lines left in or incompletely erased during the design process.

Every time I've seen "printing errors" of the nature you describe on Shapeways prints, it has, without fail, been a fault in the model, not in printing. My fault not theirs.

Voids

The upper surface of the voids is curved, almost like the holes were "melted" through and the whole floor is not smooth, it has waves across it.  I have two other printings of a similar type of car and they are very crisp.   I can buy that the flash is a design error, but have a hard time thinking that the smooth, curved surfaces of the voids would be caused by a drawing error.  

I'm no expert, so I could be wrong.

Reply to Dave

Hey Dave,

Sorry about the poor print.  That really surprises me.  I would suggest contacting Shapeways and asking about it as the other prints I've seen of that model didn't have that issue.  I'm not an expert and don't claim to be, but the print should look like the 3D spin on the preview, and those voids are not on that 3D spin.  I've never seen flash on a Shapeways product so I just can't help but wonder if there was something wrong with that setup.  Crazy!

I'd love to see pictures of your finished cars, whenever you get around to them.